Channeled warming blanket

ABSTRACT

A warming blanket incorporating channeled areas for accepting heat and/or sensor wires. The inventive blanket includes multiple layers of knitted, woven or non-woven fabrics that are welded together with ultrasonic seams to define channels through which wires for resistive heating can be placed. This composite may be produced in a continuous process, providing the composite in roll form.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority from U.S. Provisional patent application Ser. No. 60/643,354, filed on Jan. 12, 2005 the contents of which are hereby incorporated by reference in their entirety as if fully set forth herein.

TECHNICAL FIELD

This invention relates generally to warming blankets. More particularly, the invention relates to warming blankets including channeled areas for accepting heat and/or sensor wires. These channeled areas are bounded by welded zones disposed in a pattern across the warming blanket. A method of forming such a warming blanket is also provided.

BACKGROUND

Warming blankets with channels are well known in the art and are available from a variety of sources. Many of these blankets are formed by weaving two layers of cloth simultaneously, creating a blanket with a pattern of channels for accepting a heat and/or sensor wire. A limitation of the prior process is that interweaving of fabric layers does not allow for the incorporation of additional layers of material such as batting for thermal insulation. Moreover, interweaving of layers to form the channels necessitates the use of woven cloth which limits design options and which may increase cost and weight. Accordingly, the need exists for an improved channeled warming blanket that avoids these limitations.

SUMMARY

The present invention provides advantages or alternatives over the prior art by providing a warming blanket shell having multiple layers on each side welded together with ultrasonic seams to create channels through which wires for resistive heating can be placed. The wires are arranged between two opposing non-woven layers, thereby creating a low friction, low stretch channel for the wire.

According to one aspect of the invention a warming blanket shell is provided having two opposing interior layers of non-woven fabric with layers of decorative fabric disposed on each outer surface of these non-woven layers and ultrasonic weld seams joining the non-woven layers together. The ultrasonic weld seams extend in a pattern to define channels to accept heat and/or sensor wires. Optionally, a layer of high loft batting may be disposed between at least one non-woven layer and a decorative fabric outer layer. The warming blanket shell may be produced in roll form for use with automated wiring equipment.

According to another aspect of the invention a method of producing a composite warming blanket shell is provided. The method utilizes a series of rotating anvils that interact with an array of cooperating ultrasonic horns to create a pattern of ultrasonic seams, thereby forming channels which can accept heat and/or sensor wire.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of example only, with reference to the accompanying drawings which constitute a part of the specification herein and in which:

FIG. 1 is a cross section of an exemplary warming blanket composite after wiring;

FIG. 2 is an overhead view of a warming blanket composite showing an exemplary channel pattern;

FIG. 3 is a schematic view illustrating an exemplary formation line for a multi-layer warming blanket;

FIG. 4 is a cross machine view taken along line 4-4 in FIG. 3.

DETAILED DESCRIPTION

Exemplary embodiments of the invention will now by described by reference to the drawings wherein like elements are designated by corresponding reference number throughout the various views. In FIG. 1, a warming blanket 8 is shown. As illustrated the warming blanket includes a first inner layer 10 and a second inner layer 10′ disposed in opposing relation to one another. The inner layers 10 and 10′ are preferably of non-woven fibrous construction and more preferably of spun-bond non-woven fibrous construction. The inner layers 10, 10′ may be formed of fibers including polyester, polypropylene, or any other ultrasonically fusible fiber material. Although the weight of the inner layers can vary greatly, the layers should be of sufficient strength to provide a stable channel for wiring without increasing the composite stiffness significantly. Preferably, the mass per unit area of each of the inner layers 10, 10′ is between about 0.40 oz/yd² and about 1.1 oz/yd². This provides a low stretch, low friction channel through which to insert the wire.

As shown, the exterior is preferably defined by a first decorative shell fabric layer 14 and a second decorative shell fabric layer 14′. The shell fabric can be a warp knit, circular knit, nap knit micro-denier, woven, non-woven, needle punch construction formed from suitable ultrasonically fusible fibrous materials including polyester, polypropylene or the like. Although the weight can vary over a wide range, the amount of material affects the ultrasonic welding speed and efficiency. The preferable mass per unit area for the decorative shell fabric layer is in the range from about 2.5 oz/yd² to about 6.0 oz/yd².

According to one contemplated embodiment, a layer 12 may also be present between one or both decorative shell fabric layers 14 and 14′ and the corresponding inner layers 10 and 10′. In the illustrated embodiment, the layered composite comprises one layer 12 situated between the inner side of the outer shell fabric layer 14 and the outer side of the adjacent inner layer 10. Layer 12 can be a batting layer of relatively high loft material for thermal insulation. In this particular example, the outer shell fabric layer 14 defines the top of the blanket 8 so that the batting traps the heat generated and radiates such heat downwards towards the user. Furthermore, the batting is particularly useful in creating both a three-dimensional structure to the final composite and in masking the tactile perception of the heating wires by the user. The batting is preferably a polyester resin-bond with a loft of between 0.125 inches and 0.50 inches. It should have adequate wash stability, and should not contribute to the overall flammability of the composite.

As previously indicated and according to a contemplated practice, the warming blanket 8 is further defined by a plurality of ultrasonic seams which create welded areas 16 (FIG. 2) where the fabric has been ultrasonically fused and non-welded areas 18 where the fabric has not been ultrasonically fused. The welded areas 16 define fused seams of pre-determined length and width in which the outer layers 14 and 14′ as well as the inner layers 10 and 10′ and the optional layer 12 are linked together. The formation of these seams in which the distances between the outer layers 14 and 14′ and between the inner layers 10 and 10′ have been dramatically decreased compared to the corresponding distance in the non-welded areas 18, creates channels 20 in the non-welded areas. These channels are situated between the inner layers 10 and 10′ and extend in patterns parallel to the welded areas 16. As shown in FIG. 1, heat/sensor wire 22 can be inserted in the channels 20 between the two inner layers 10 and 10′ utilizing automated wiring equipment.

By way of example only, and not limitation FIG. 2 shows one exemplary pattern of channels defining welded and non-welded areas, formed utilizing the method described herein. As shown, ultrasonic seams defined by the welded areas extend longitudinally along the planar dimension of the warming blanket and define a series of channels that can accept heat and/or sensor wire. The seams are represented by the welded areas 16 which are of a predetermined length and width. The majority of the blanket is non-welded 18.

FIG. 3 provides one non-limiting example of a process for forming the inventive warming blanket composite shell. In the illustrated arrangement, the let-off rolls are arranged such that the two non-woven layers 10 and 10′ are in adjacent opposing relation. The optional batting layer 12, if present, is on an outer side of one or both of the non-woven layers, and the decorative shell fabrics 14 and 14′ are on either side of the entire composite. During processing, the layers proceed through a gap between an array of ultrasonic horns 24 and a series of rotating anvils 26. One anvil wheel is provided for each channel boundary and the anvils can be individually actuated in an up and down motion. When an anvil is in the “up” position, the horns direct the relatively high frequency ultrasonic vibration onto the fabric layers held in close proximity by the supporting rotating anvils causing localized frictional heating along a narrow, relatively continuous band and concomitant welding to form a seam. When the anvil is in the “down” position, the fabric layers pass through with no welding occurring.

The anvils can be computer controlled to create a pre-determined pattern with a repeat length that is programmable into the controller. Thus, conventional warming blanket design which necessitates channel termination prior to reaching the edge of the blanket shell to allow for normal electrical connections is easily achieved. Blankets of any length can be produced, and blankets of different lengths can be produced on the same equipment with only minor changes to the program. In addition, the anvils 26 are attached to a frame 28 (shown in FIG. 4) and can be positioned across the frame with variable spacing. Thus, the number of channels, the spacing between the channels, and the length of each individual channel can be adjusted without major equipment modifications in a timely and cost effective manner. Furthermore, uniform heating is assured by the uniform disposition of channels and electrical heating wires across the length and width of the blanket. This also avoids contact or close proximity of adjacent wires and concomitant overheating.

This method of production allows the blanket composite to be manufactured in roll form, thus avoiding the costly and labor intensive cut and sew steps required with the production of individual blankets. Moreover, automated wiring equipment can only be employed if the composite is in roll form.

As a variation of the described method, it is contemplated that the first and second non-woven layers may be ultrasonically welded to form channels for heat/sensor wires. Subsequently, the first and second outer decorative fabric layers may be attached to the fused non-woven layers by any attachment means available to those in the art including sewn seams, adhesion or the like.

The inventive concepts may be further understood by reference to the following non-limiting example.

EXAMPLE 1

A composite is formed with a 4.5 oz/yd² napped circular knit fabric, a layer of 1.75 oz/yd² polyester batting (0.25 inch loft), two layers of 1.1 oz/yd² polyester spun-bond non-woven, and another layer of the 4.5 oz/yd² napped circular knit polyester. The composite is welded together in a pattern such as that displayed in FIG. 2. The composite is then cut into individual blankets and a heater wire is inserted in a serpentine pattern throughout the channels such that the end point is the original starting location. 

1. A warming blanket composite shell comprising: a first non-woven layer; a second non-woven layer; a first decorative fabric layer disposed on an outer surface of said first non-woven layer; a second decorative fabric layer disposed on an outer surface of said second non-woven layer; and a plurality of ultrasonic weld seams bonding the non-woven layers and decorative fabric layers together, wherein the ultrasonic weld seams are arranged in a pattern defining boundaries of wire accepting channels.
 2. The invention of claim 1 wherein said composite shell is in roll form.
 3. The invention of claim 1 wherein at least a portion of said weld seams are discontinuous along the length of the warming blanket composite shell.
 4. The invention of claim 1 wherein said first and said second non-woven layers comprise spun-bond non-woven fabrics.
 5. The invention of claim 1 wherein said first and said second non-woven layers are characterized by a fabric weight about 0.40 oz/yd² to about 1.1 oz/yd².
 6. The invention of claim 1 wherein an ultrasonically fusible batting layer is disposed between said first non-woven layer and said first decorative fabric layer.
 7. The invention of claim 6 wherein said batting layer is polyester resin-bond batting.
 8. The invention of claim 6 wherein said batting layer is characterized by a loft of about 0.125 inches to about 0.50 inches.
 9. The invention of claim 6 wherein said batting layer is characterized by a mass per unit area of about 1.1 ounces per square yard.
 10. The invention of claim 1 wherein said first and said second decorative fabric layers are selected from the group consisting of a warp knit, circular knit, nap knit micro-denier, woven, non-woven, and needle punch fabric.
 11. The invention of claim 10 wherein said first and said second decorative fabric layers are nap knit micro-denier fabric.
 12. The invention of claim 10 wherein said first and said second decorative fabric layers are characterized by a fabric weight of about 2.5 oz/yd² to about 6.0 oz/yd².
 13. The invention of claim 1 wherein said weld seams comprise elongate lines of a predetermined length.
 14. A method of producing a composite warming blanket shell comprising the steps of; (a) arranging let-off rolls such that two non-woven layers are adjacent to one another; and (b) disposing of a first and second decorative fabric layers on the outer surfaces of said non-woven layers; and (c) applying a plurality of ultrasonic weld seams across the non-woven layers and decorative fabric layers thereby bonding the non-woven layers and decorative fabric layers together such that the ultrasonic weld seams are arranged in a pattern defining boundaries of channels adapted to accept wire elements.
 15. The method of claim 14 wherein said first and said second non-woven layers comprise spun-bond non-woven fabrics.
 16. The method of claim 14 wherein said first and said second non-woven layers comprise a fabric characterized by a weight of about 0.40 oz/yd² to about 1.1 oz/yd².
 17. The method of claim 14 comprising the further step of disposing a batting layer between said first non-woven layer and said first decorative fabric layer.
 18. The method of claim 17 wherein said batting layer is polyester resin-bond batting.
 19. The method of claim 17 wherein said batting layer is characterized by a loft of about 0.125 inches to about 0.50 inches.
 20. The method of claim 17 wherein said batting layer is characterized by a mass per unit area of about 1.1 ounces per square yard.
 21. The method of claim 14 wherein said first and said second decorative fabric layers are selected from the group consisting of a warp knit, circular knit, nap knit micro-denier, woven, non-woven, and needle punch fabric.
 22. The method of claim 21 wherein said first and said second decorative fabric layers are nap knit micro-denier fabric.
 23. The method of claim 21 wherein said first and said second decorative fabric layers are characterized by a fabric weight of about 2.5 oz/yd² to about 6.0 oz/yd². 